While we often talk about puberty's effect on the body, what gets overlooked are the fascinating changes that happen in the brain. Puberty, in fact, begins in the brain, and lasts as long as five years. And during this extended process, the brain undergoes its own transformation, thanks to estrogen and testosterone. Shannon Odell details what we know -- and still don't know -- about puberty. This TED-Ed lesson was directed by Biljana Labović, narrated by Alexandra Panzer and Adrian Dannatt, with music by Weston Fonger.